Arsenic contamination in irrigation water, agricultural soil and maize crop from an abandoned smelter site in Matehuala, Mexico

[Display omitted] •As contaminates water, soils and maize crops in Matehuala, San Luis Potosi, Mexico.•High CEC, total N, P, and OM explain lower bioconcentration of As.•High soil EC explains higher bioconcentration of As.•Gypsum and calcite play a key and contrasting role on the mobility of As in soils.•Information on retention mechanisms of As in calcic and gypsic soils is limited. Mobility of Arsenic (As) from metallurgical wastes in Matehuala, Mexico has been accounted for ultra-high concentration of As in water (4.8–158mg/L) that is used for recreational purposes as well as cultivation of maize. In this study, we (i) measured As concentrations in soils irrigated with this water, (ii) investigated the geochemical controls of available As, and (iii) measured bioaccumulation of As in maize. Water, soil, and maize plant samples were collected from 3 different plots to determine As in environmental matrices as well as water soluble As in soils. Soil mineralogy was determined by X-ray diffraction analysis. Bioaccumulation of As in maize plants was estimated from the bioconcentration and translocation factors. We recorded As built-up in agricultural soils to the extent of 172mg/kg, and noted that this As is highly soluble in water (30% on average). Maize crops presented high bioaccumulation, up to 2.5 times of bioconcentration and 45% of translocation. Furthermore, we found that water extractable As was higher in soils rich in calcite, while it was lower in soils containing high levels of gypsum, but As bioconcentration showed opposite trend. Results from this study show that irrigation with As rich water represents a significant risk to the population consuming contaminated crops.